Since a viscosity of a lubricating oil (operation oil) of a transmission is high before a warming-up of the transmission that is mounted to a vehicle is completed, an efficiency of a power transmission of the transmission is reduced, and a fuel consumption of the vehicle is deteriorated. In this case, the transmission is an automatic transmission.
According to JP-2002-176794A, a technology is disclosed to accelerate the warming-up of the transmission to suppress a deterioration of the fuel consumption, in a hybrid vehicle provided with an engine and a motor which are used as power sources of the hybrid vehicle. Specifically, the transmission is placed at a position in the vicinity of the motor. When a temperature of the lubricating oil of the transmission is less than a predetermined value, a driving force of the engine is reduced, and a driving force of the motor is increased. Therefore, a heat generation quantity of the motor is increased to increase the temperature of the lubricating oil.
However, a heat loss of the motor and the transmission is not completely contributed to an increasing of the temperature of the lubricating oil, and a part of the heat loss is discharged to external. Therefore, even though the heat generation quantity of the motor is increased, when a quantity of the heat loss causing the increasing of the temperature of the lubricating oil is small, the temperature of the lubricating oil cannot be efficiently increased.
According to JP-2002-176794A, since only the driving force of the motor is increased to increase the heat generation quantity of the motor, the temperature of the lubricating oil may be insufficiently increased. Thus, an accelerated effect of the increasing of the temperature of the lubricating oil and a suppressed effect of the deterioration of the fuel consumption cannot be sufficiently improved.